These are the most common groups who are asked by HMRC to complete a tax return:

• Self-employed

• Company directors

• Income from savings and investments that are £10,000 or above

• Income from rental (after expenses) of £2,500 or above

• Income is over£100,000 in a tax year

• You need to pay capital gains tax (CGT).  This following link explains CGT . It talks about CGT on the sale of shares. The principles are the same whether you are selling shares or any other assets http://www.southsideaccountants.co.uk/diary/2010/01/17/what-is-the-tax-position-if-listed-company-shares-sold-at-a-loss/

• You want to claim certain expenses. For example as an employee you want to claim professional subscriptions of £2,500 or more.

• You live or work abroad

The onus is on you to complete your tax return. If you are not sure whether you need to complete a tax return please contact HMRC or ask your accountant.

Do I need an Accountant to complete a tax return?

You do not need an accountant to complete a tax return. However, to ensure that you pay the minimum amount of tax within the law, it would be best to employ an accountant. http://www.southsideaccountants.co.uk/diary/2009/11/17/check-your-accountant-is-qualified/

What is the deadline  for completing tax returns?

• There is a deadline of  31/10 if you complete a paper tax return.

• If you complete a tax return online the deadline is 31/1.

What if I don’t complete a tax return, when I am required?

You will get an automatic penalty of £100. After several reminders from HMRC, you will get a big fine as high as twice your tax bill plus  interest.

http://www.southsideaccountants.co.uk/taxation-services.html#perstax